Roll stabilizer for a boat

Claim 2

A passive non-linear energy absorbing dynamic mass system for limiting the roll of a floating vessel comprising a moving mass, a longitudinal guide member, means movably supporting the mass on the guide member for substantially free and undamped movement along the full length of the guide member, mounting means for mounting the guide member on the vessel with the path of movement of the mass extending transversely to the roll axis of the vessel, the energy absorbing means secured to the guide member and positioned at separated points along said path for limiting the length of free movement of the mass, the energy absorbing means absorbing substantially all the kinetic energy of the mass from impacts with the moving mass and dissipating it as heat to prevent recoil acceleration of the mass on impact, the amount of free movement of the mass along the guide means between the energy absorbing means being substantially greater than the motion accommodation distance of the energy absorbing means, the mass when the vessel is in a static level position being free along the full length of the guide member between the energy absorbing means of any forces tending to restore the mass to a central position.

Claim 3

Apparatus of claim 1 wherein the weight of the moving mass is of the order of 1/2% of the displacement weight of the vessel.

Claim 4

Apparatus of claim 1 further including releasable locking means secured to the guide member and engageable with the mass for securing the mass against movement along said guide member thereby to disable the system.

Claim 5

Apparatus of claim 1 wherein the energy absorbing means comprises blocks of polyurethane foam.

Claim 6

Apparatus of claim 1 wherein said energy absorbing means includes a hydraulic shock absorbing device engaged by the mass at the limits of travel at either end of said guide member.

Claim 7

Apparatus of claim 1 wherein said energy absorbing means includes a body of self-restoring plastic foam material engaged and compressed by the mass at either end of said guide member.

Claim 8

Apparatus of claim 6 wherein the body of plastic foam varies in stiffness throughout the length of the body in the direction of the moving mass.

Claim 9

Apparatus of claim 1 wherein the mounting means supports the guide member at a height above the roll axis of the vessel that is substantially greater than the ratio of the acceleration of gravity to the square of the natural roll frequency of the vessel.

Claim 10

Apparatus for stabilizing a rolling vessel, comprising: means supporting a weight from a vessel above the roll center for free and undamped movement relative to the vessel, means restricting the movement of the weight relative to the vessel to a path transverse to the roll axis of the vessel, stop means spaced along the path for limiting the movement of the weight along said path, said supporting means providing unstable support of the weight when the vessel is in a static level position, whereby the weight tends to move toward and remain against the stop means at either end of the path of the weight with the slightest tilt of the vessel in either direction, said restricting means affording free undamped transverse motion of the weight between the stop means, the stop means including mechanical energy absorbing and dissipating means having very low resilience so that the weight does not rebound along the path following impact with the stop means, the total motion accommodation distance of the stop means being substantially less than the distance along the path between the stop means whereby the weight is free of contact with the stop means during a substantial portion of its movement along said path.

Claim 11

Apparatus for stabilizing a rolling vessel, comprising: means supporting a weight from a vessel above the roll center for free and undamped movement relative to the vessel, means restricting the movement of the weight relative to the vessel to a path transverse to the roll axis of the vessel, stop means spaced along the path for limiting the movement of the weight along said path, said supporting means providing unstable support of the weight when the vessel is in a static level position, whereby the weight tends to move toward and remain against the stop means at either end of the path of the weight with the slightest tilt of the vessel in either direction, said restricting means affording free undamped transverse motion of the weight between the stop means, the stop means including mechanical energy absorbing and dissipating means having very low resilience so that the weight does not rebound along the path following impact with the stop means, the total motion accommodation distance of the stop means being substantially less than the distance along the path between the stop means whereby the weight is free of contact with the stop means during a substantial portion of its movement along said path.